From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Technical memorandum regarding modifications to the Phantom III tappet to address wear issues.
| Identifier | ExFiles\Box 96\2\ scan0291 | |
| Date | 5th July 1938 | |
| 354 BY/NS.{Norman Scott} C. BY.{R.W. Bailey - Chief Engineer} C. Mx.{John H Maddocks - Chief Proving Officer} C. Em C. LA.{L. A. Archer} C. RM{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} Files DA.{Bernard Day - Chassis Design}9/G.5.7.38. PHANTOM 111 - TAPPET WEAR. Please receive herewith :- E.CD.782 Modified Tappet, Phantom 111. As a result from the suggestion by BY.{R.W. Bailey - Chief Engineer} that a probable cause for the tappet wear, which has from time to time occurred, is the hydraulic effect of the tappet and the tappet spring washer in the tappet guide, we have demonstrated on a rig that a considerable pressure can be obtained in the tappet when full of oil, and that the pressure varies considerably according to the leakage factor between the washer and the guide. The design shows a modification to increase the oil leakage from the tappet guide by increasing the bore of the tappet a little and by making the spring washer square. The side clearance of the tappet in the fork is also increased by .001" as the standard tappets tighten up a little, at this point when assembled in the tappet block. We have also added a small lead-in chamfer for the top bearing of the tappet to facilitate assembly. Mx.{John H Maddocks - Chief Proving Officer} has arranged with LA.{L. A. Archer} to fit an engine with half the tappet spring washers to this design and the other half with oversize diameter of washer (.620" outside diameter) to demonstrate the actual effect of the two conditions when running in an engine (the standard washer is .600 diameter). Will you please prepare the necessary details for this job and issue experimentally. If the tappet load is considerably reduced by this alteration we could again try some tappets without the chromium plating on the face. DA.{Bernard Day - Chassis Design} | ||